The advantage of a bus topology is that it is easy to extend or to create; all you need are the connecting wires. You do not need any additional special devices such as hubs or switches. The...
The logical topology for a bus topology is the same it is a bus topology
advantage is easy to install
Bandwidth is shared between all nodes; each additional node causes the entire network to run inherently slower.
To prevent signals from being echoed back through the network
Dr. Machio Kaku on the Cheapest Way to Terraform Mars